Exhaust hood and method for controlling the operation of an exhaust hood

ABSTRACT

An exhaust hood has a fan apparatus for drawing away discharge air from a cooking appliance, which is arranged beneath the exhaust hood and which has at least one cooking area. A temperature detection device detects a temperature of at least one cooking area of the cooking appliance and a cooking vapor detection device detects cooking vapors in the discharge air which is drawn away by suction by the fan apparatus. A control device of the exhaust hood switches on the fan apparatus depending on a temperature which is detected by the temperature detection device and controls a suction-removal power of the fan apparatus depending on cooking vapors which are detected by the cooking vapor detection device.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority, under 35 U.S.C. §119, of German application DE 10 2012 024 975.6, filed Dec. 20, 2012; the prior application is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exhaust hood and to a method for controlling the operation of an exhaust hood.

The prior art discloses various measures for switching on and for controlling the power of a fan apparatus of an exhaust hood. In addition to manually switching on and selecting a power level by means of a suitable operator control apparatus on the exhaust hood, various automatic control methods are known in particular.

German patent DE 25 18 750 B2 and German published patent application DE 39 22 090 A1 each describe an exhaust hood above a stove, in which exhaust hood a rotation speed of an electric motor of a ventilator is controlled in an continuously variable manner depending on a temperature of the cooking vapors. To this end, the control device is moved to a readiness position as soon as a cooking plate of the stove is switched on. The temperature is monitored by means of at least one temperature sensor in the form of an NTC resistor in the extraction region and at least one further temperature sensor in the form of an NTC resistor on the outside of the housing of the exhaust hood.

For the purpose of controlling the power level of the ventilator motor of an exhaust hood, the cooking vapors' can also be detected and evaluated by means of infrared sensors (see, German published patent application DE 41 05 87 A1), ultrasound sensors (see, U.S. Pat. No. 6,324,889 B1 and European patent application EP 1 001 226 A1), laser sensors (see, U.S. Pat. No. 7,442,119 B2 and German published patent application DE 10 2005 015 754 A1) or gas sensors (cf. EP 1 452 804 A1).

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide an exhaust hood and a method of controlling the exhaust hood which overcome the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for an improved exhaust hood and an improved method for controlling the operation of an exhaust hood with automatic switch-on and automatic power control.

With the foregoing and other objects in view there is provided, in accordance with the invention, an exhaust hood for placement above a cooking appliance having at least one cooking area, comprising:

a fan apparatus for suctioning away discharge air from the cooking appliance arranged beneath the exhaust hood;

a temperature detection device for detecting a temperature of the at least one cooking area of the cooking appliance;

a cooking vapor detection device for detecting cooking vapors contained in the discharge air drawn away by suction with said fan apparatus; and

a control device connected to receive information from said temperature detection device and from said cooking vapor detection device, said control device being configured for switching on said fan apparatus in dependence on a temperature detected by said temperature detection device and for controlling a suction-removal power of said fan apparatus in dependence on cooking vapors detected by said cooking vapor detection device.

In other words, the exhaust hood of the invention comprises a fan apparatus for drawing away discharge air from a cooking appliance, which is arranged beneath the exhaust hood and has at least one cooking area, by suction, a temperature detection device for detecting a temperature of at least one cooking area of the cooking appliance, and a cooking vapors detection device for detecting cooking vapors' in the discharge air which is drawn away by suction by means of the fan apparatus. A control device of the exhaust hood is designed to switch on the fan apparatus depending on a temperature which is detected by the temperature detection device and to control a suction-removal power of the fan apparatus depending on cooking vapors' which are detected by the cooking vapors detection device.

In this exhaust hood, both the processes of switching on the fan apparatus and controlling the suction-removal power of the fan apparatus are performed automatically.

The distinguishing measures for automatically switching on the fan apparatus and for controlling the suction-removal power of the fan apparatus allow the exhaust hood to react very quickly and reliably to cooking vapors' which are produced at the cooking appliance. Monitoring the temperature of the at least one cooking area of the cooking appliance allows the fan apparatus to be switched on very quickly once the cooking appliance has been put into operation, that is to say as soon as it is possible for cooking vapors' to be produced at the cooking appliance. Therefore, cooking vapors' which are produced can be routed very quickly to the exhaust hood and, in particular, also to the cooking vapors detection device of said exhaust hood. The cooking vapors detection device can in this way very quickly detect the cooking vapors' and accordingly control of the power of the fan apparatus. In other words, the advantages of temperature measurement of the cooking areas, which is generally only very approximate, and relatively accurate detection of cooking vapors' are combined with one another in the exhaust hood according to the invention.

Furthermore, this exhaust hood does not need to be coupled to the cooking appliance by lines or wirelessly in order to be able to implement these automatic processes, and therefore the exhaust hood does not have to have a special interface. The exhaust hood and the cooking appliance can therefore be designed and installed as appliances which are independent of one another.

The cooking appliance which is arranged beneath the exhaust hood is, in particular, a heat-generating cooking appliance, preferably a stove, and in particular an electronic cooking appliance. The cooking appliance has, in particular, one, two, three, four or more cooking areas which are arranged next to one another. In this case, the cooking areas correspond, in particular, to the burners or cooking plates which are prespecified by the cooking appliance, but can also comprise two or more such burners or cooking plates.

The exhaust hood according to the invention has a fan apparatus. The term “fan apparatus” in this connection is intended to denote any kind of apparatus which is suitable for generating a stream of discharge air from the cooking appliance beneath the exhaust hood upward into the exhaust hood. The stream of discharge air is preferably conveyed further out of the exhaust hood again by a discharge-air channel. The fan apparatus preferably has at least one fan, ventilator or the like. The fan apparatus preferably has at least one electric motor for driving the fan, ventilator etc. The electric motor of the fan apparatus is preferably actuated, that is to say in particular switched on and controlled in respect of its rotation speed, by the control device of the exhaust hood.

The exhaust hood according to the invention further has a temperature detection device for detecting a temperature of at least one cooking area of the cooking appliance. That is to say, the temperature detection device is a constituent part of the exhaust hood and is integrated into said exhaust hood or is connected to the said exhaust hood, and therefore the exhaust hood does not require an interface to the cooking appliance. The temperature detection device is designed, in particular, in order to detect the temperatures of all of the cooking areas of the cooking appliance. The temperature detection device preferably has one, two, three, four or more temperature sensors for detecting a temperature of a cooking area of the cooking appliance. These temperature sensors are preferably arranged on the exhaust hood outside or at least in a boundary region of a stream of discharge air. Furthermore, the temperature detection device preferably also has one, two, three, four or more temperature sensors for detecting an ambient temperature of the exhaust hood.

The control device of the exhaust hood switches on the fan apparatus of the exhaust hood depending on a temperature which is detected by this temperature detection device. In this context, this is intended to be understood to mean, in particular, a dependency on a temperature value of a cooking area, on an average temperature value of all of the cooking areas, on a maximum temperature value of all of the cooking areas, on a temperature gradient of one of the abovementioned temperature values over time, on a difference value between one of the abovementioned temperature values and an ambient temperature of the exhaust hood, on a temperature gradient of one of the abovementioned difference values over time, and the like. The control device switches on the fan apparatus as soon as the respective measurement value reaches or exceeds a prespecified threshold value, preferably reaches or exceeds said threshold value for at least a predetermined period of time.

The exhaust hood according to the invention has a cooking vapors detection device for detecting cooking vapors' in the discharge air which is drawn away by suction by means of the fan apparatus. The cooking vapors detection device preferably has one, two, three or more cooking vapors detection sensors. These cooking vapors detection sensors can be connected upstream and/or downstream of the fan apparatus in the stream of discharge air. These cooking vapors detection sensors can also be connected upstream and/or downstream of a filter apparatus, if present, in the stream of discharge air. In this context, the term “cooking vapors detection sensor” is intended to denote any kind of apparatus which is suitable for detecting the presence and, in particular, also the quantity and/or the type of cooking vapors'. Suitable cooking vapors detection sensors include, in particular, infrared sensors, ultrasound sensors, laser sensors, gas sensors and similar sensors.

The control device of the exhaust hood controls a suction-removal power of the fan apparatus depending on cooking vapors which are detected by the cooking vapors detection device. In this context, this is intended to mean, in particular, a dependency on a quantity of cooking vapors, composition of cooking vapors, temperature of cooking vapor, type of cooking vapor etc. The suction-removal power of the fan apparatus is preferably controlled in a continuously variable manner or at prespecified power levels. In this context, controlling the suction-removal power comprises, in particular, increasing, decreasing and keeping constant the suction-removal power or the power level of the fan apparatus. In this case, the suction-removal powers or power levels of the fan apparatus are preferably controlled by controlling the rotation speed of an electric motor and/or of a ventilator of the fan apparatus.

In a preferred refinement of the invention, the temperature detection device has at least one infrared sensor for detecting a temperature of at least one cooking area of the cooking appliance. Contact-free temperature detection by the infrared sensor constitutes a particularly simple and at the same time sufficiently accurate measurement method. The level of accuracy in temperature detection of the at least one cooking area which can be achieved in this way is adequate for the exhaust hood of the invention since the temperature detection is intended merely to trigger switch-on of the fan apparatus but the suction-removal power is not intended to be controlled in an accurate manner on demand.

In a preferred refinement of the invention, the control device is designed in order to switch on the fan apparatus at a low power level depending on a temperature which is detected by the temperature detection device. The above statements correspondingly apply in relation to control depending on a temperature. Switching on the fan apparatus at a low power level initially causes only a low level of energy consumption and a low noise level. The power of the fan apparatus is increased only when cooking vapors' are also actually detected with the aid of the cooking vapors detection device in the discharge air which has been drawn away by suction. The low power level corresponds, in particular, to a lowest power level of the fan apparatus.

In a further preferred refinement of the invention, the temperature detection device is designed in order to detect the temperatures of several cooking areas of the cooking appliance separately; the fan apparatus is designed in order to generate separate streams of discharge air from the individual cooking areas of the cooking appliance; and the control device is designed in order to control the separate streams of discharge air of the fan apparatus depending on the temperatures which are detected by the temperature detection device. In this refinement, it is possible to draw away discharge air by suction mainly only from the cooking areas at which cooking vapors are actually produced. As a result, the energy consumption and/or the development of noise by the exhaust hood can be reduced.

In a yet further preferred refinement of the invention, the control device is designed in order to switch off the fan apparatus depending on a temperature which is detected by the temperature detection device, depending on cooking vapors' which are detected by the cooking vapors detection device, in a time-dependent manner and/or by manual operator control.

In a yet further preferred refinement of the invention, the exhaust hood is additionally equipped with an operator control apparatus by means of which a user can manually switch on the fan apparatus and/or can manually select the power levels of the fan apparatus.

With the above and other objects in view, there is also provided a method of controlling an exhaust hood. The method according to the invention for controlling the operation of an exhaust hood which is arranged above a cooking appliance having at least one cooking area comprises the steps of detecting a temperature of at least one cooking area of the cooking appliance; switching on a fan apparatus depending on the detected temperature; detecting cooking vapors in the discharge air which is drawn away by suction by means of the fan apparatus; and controlling a suction-removal power of the fan apparatus depending on the cooking vapors which are detected.

The same advantages as have been explained in connection with the exhaust hood of the invention can be achieved using this method. Therefore, in respect of the advantages, definitions of terms and preferred refinements of the said method, reference is therefore made at this juncture only to the above statements in connection with the exhaust hood of the invention.

In a preferred refinement of the invention, the fan apparatus is switched on at a low power level depending on the detected temperature.

In a further preferred refinement of the invention, the temperatures of several cooking areas of the cooking appliance are detected separately, and separate streams of discharge air of the fan apparatus from individual burners of the cooking appliance are controlled depending on the detected temperatures.

In a yet further preferred refinement of the invention, the fan apparatus of the exhaust hood is switched off depending on a detected temperature of at least one cooking area of the cooking appliance, depending on detected cooking vapors, in a time-dependent manner and/or by manual operator control.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a exhaust hood and method for controlling the operation of an exhaust hood, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

The sole FIGURE is a schematic illustration of an exemplary embodiment of an exhaust hood according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the sole FIGURE of the drawing in detail, there is shown an exemplary embodiment of an exhaust hood according to the present invention.

The exhaust hood 14, which is also referred to as an extractor hood, is arranged in a conventional way above a stove top, or stove 10 for short, having a plurality of burners 12. The burners 12 can have the same or different sizes and shapes. In addition, the burners 12 can be operated independently of one another, that is to say individually switched on and controlled in respect of their respective heating power. In this exemplary embodiment, each of the total of four burners 12 at the same time forms a cooking area within the meaning of the invention. In other exemplary embodiments, two burners 12, for example, can be combined to form a cooking area.

The exhaust hood 14 has a fan apparatus 16 comprising an extractor or ventilator in a discharge-air channel 17. The ventilator is driven by means of an electric motor (not illustrated) of the fan apparatus 16. The driven ventilator generates a stream of discharge air from the burners 12 of the stove 10 upward into the exhaust hood 14 and further into the discharge-air channel 17. The discharge air is routed, for example, directly out of a building or passed to a discharge-air system via the discharge-air channel 17.

A non-illustrated filter apparatus is optionally arranged on the lower face of the exhaust hood, the said lower face facing the burners 12. The filter apparatus is fitted, for example, in a detachable manner so as to allow same to be replaced or cleaned as required.

A plurality of (in this exemplary embodiment four) infrared sensors 18 are arranged in the region of the lower edge of the exhaust hood 14. The four infrared sensors together form a temperature detection device within the meaning of the invention. The infrared sensors 18 are each designed and conceived in order to detect a temperature of a burner 12 of the stove 10. They are preferably positioned in the circumferential boundary region of the exhaust hood 14 and therefore outside the stream of discharge air as far as possible. If a burner 12 is put into operation, the temperature of the burner 12 increases, as does that of the cooking utensil which is positioned on it, and this can be detected by the infrared sensors 18.

Depending on the embodiment, further temperature sensors can additionally be provided on the exhaust hood 14. The further temperature sensors would detect the temperature of the area surrounding the exhaust hood.

The infrared sensors 18 and possibly the further temperature sensors are connected to a control device 24 of the exhaust hood 14. The control device 24 which is illustrated separately in the FIGURE is preferably integrated in the exhaust hood 14.

As indicated in the FIGURE, at least one cooking vapor sensor 20, for example in the form of an ultrasound sensor, an infrared sensor, a laser sensor or the like, is arranged in the exhaust hood 14 upstream of the ventilator of the fan apparatus 16 in the stream of discharge air. This at least one cooking vapor sensor 20, which is exposed to the exhaust stream, is intended to detect the presence and the concentration of cooking vapors in the stream of discharge air of the exhaust hood 14.

As likewise indicated in the FIGURE, at least one further cooking vapor sensor 22, for example in the form of a gas sensor or the like, is arranged in the discharge-air channel 17 of the exhaust hood 14 downstream of the ventilator of the fan apparatus 16 in the stream of discharge air. This at least one further cooking vapor sensor 22 is intended to detect the composition of cooking vapors in the stream of discharge air of the exhaust hood 14.

The at least one cooking vapor sensor 20 and the at least one further cooking vapor sensor 22 form a cooking vapor detection device of the invention. In other exemplary embodiments, this cooking vapor detection device can also have only the at least one cooking vapor sensor 20 or only the at least one further cooking vapor sensor 22.

The at least one cooking vapor sensor 20 and the at least one further cooking vapor sensor 22 are likewise connected to the control device 24 of the exhaust hood 14.

The control device 24 of the exhaust hood 14 controls the fan apparatus 16 depending on the received measurement signals from the temperature detection device and the cooking vapor detection device as follows.

In the starting state, that is to say in the non-operative state or standby state of the exhaust hood 14, the infrared sensors 18 monitor the temperatures of the burners 12 of the stove 10. The temperature values which are detected by the infrared sensors 18 are compared with a respective prespecified threshold value in the control device 24. If a temperature value reaches this prespecified threshold value, the control device 24 switches on the electric motor of the fan apparatus 16 at a low power level. Here, the term “low power level” is defined as a relative term that depends on the various power settings of the exhaust fan, which may be discreetly switchable among various power levels, or with endlessly variable gradations (from low to high power level). In this case, the prespecified threshold value for the temperature is considerably greater than room temperature, and is, for example, 40° C., 45° C., 50° C., 55° C., 60° C. or more.

In other exemplary embodiments, instead of a comparison between a temperature value and a threshold value, an average temperature value of all of the burners 12, a maximum temperature value of all of the burners 12, a difference value between the temperature of one burner 12 and an ambient temperature, a difference value between the average temperature of all of the burners 12 and an average ambient temperature, a difference value between the maximum temperature of all of the burners 12 and an average or maximum ambient temperature or the like can also be compared with a corresponding prespecified threshold value. It is furthermore also possible to compare a temperature gradient of the abovementioned measurement values over time with a corresponding prespecified threshold value.

The fan apparatus 16 is preferably first switched on by the control device 24 when the prespecified threshold value is reached or exceeded for a prespecified period of time. In this way, it is possible to compensate for, for example, measurement errors, and continuous switching on and switching off of the fan apparatus 16 at the limits of the threshold value can be avoided.

If the fan apparatus 16 is now switched on at a low power level, it generates a weak stream of discharge air from the burners 12 upward into the exhaust hood 14. The sensors 20, 22 of the cooking vapor detection device then detect cooking vapors in this stream of discharge air. If there are no cooking vapors in the stream of discharge air or cooking vapors cannot be detected in the stream of discharge air, the fan apparatus 16 continues to operate at the low power level.

If considerable cooking vapors are produced on the stove 10, these are detected by the sensors 20, 22 of the cooking vapor detection device in the exhaust hood 14. The control device 24 then controls the suction-removal power of the fan apparatus 16 or the rotation speed of the electric motor of the ventilator in accordance with the detected cooking vapors, for example in a continuously variable manner or at prespecified power levels. In this case, the suction-removal power is increased, lowered or kept substantially constant in accordance with the measurement values from the cooking vapor detection device.

Although not illustrated, the exhaust hood 14 can optionally be additionally equipped with an operator control apparatus. This operator control apparatus is then likewise connected to the control device 24. A user can manually switch on and manually adjust the power level of the fan apparatus 16, as required, by means of the operator control apparatus. Manual operation of the exhaust hood 14 may have priority over the above-described automatic control.

The exhaust hood can be switched off in different ways. For example, the control device 24 can switch off the fan apparatus 16 of the exhaust hood 14 again, for example, when the sensors 20, 22 of the cooking vapor detection device no longer detect any cooking vapors, when the temperature which is detected by the infrared sensors 18 of the temperature detection device fall below the prespecified threshold value again, by manual operation of a corresponding operator control apparatus by a user, when a predetermined period of operation of the fan apparatus 16 is reached, and the like. It goes without saying that combinations of these conditions are also feasible and the respective conditions preferably have to be met for a predetermined period of time.

In a modification of the above-described exemplary embodiment, the temperature detection device is designed such that it can detect the temperatures of the individual burners 12 of the stove 10 separately. In this case, it is feasible to generate a stream of discharge air with the fan apparatus 16 with a focus on the respectively used burner 12. To this end, the fan apparatus 16 has, for example, a plurality of ventilators and/or air flaps which can be actuated by the control device 24. 

1. An exhaust hood for placement above a cooking appliance having at least one cooking area, comprising: a fan apparatus for suctioning away discharge air from the cooking appliance arranged beneath the exhaust hood; a temperature detection device for detecting a temperature of the at least one cooking area of the cooking appliance; a cooking vapor detection device for detecting cooking vapors contained in the discharge air drawn away by suction with said fan apparatus; and a control device connected to receive information from said temperature detection device and from said cooking vapor detection device, said control device being configured for switching on said fan apparatus in dependence on a temperature detected by said temperature detection device and for controlling a suction-removal power of said fan apparatus in dependence on cooking vapors detected by said cooking vapor detection device.
 2. The exhaust hood according to claim 1, wherein said temperature detection device comprises at least one infrared sensor disposed for detecting the temperature of the at least one cooking area of the cooking appliance.
 3. The exhaust hood according to claim 1, wherein said control device is configured to switch on said fan apparatus at a relatively low power level if a relatively low temperature is detected by said temperature detection device.
 4. The exhaust hood according to claim 1, wherein: said temperature detection device is configured for detecting respective temperatures of a plurality of cooking areas of the cooking appliance separately; said fan apparatus is configured for generating separate streams of discharge air from the individual cooking areas of the cooking appliance; and said control device is configured to control the separate streams of discharge air of said fan apparatus depending on the respective temperatures detected by said temperature detection device.
 5. The exhaust hood according to claim 1, wherein said control device is configured to switch off said fan apparatus depending on a temperature detected by said temperature detection device, depending on the cooking vapors detected by said cooking vapor detection device, in a time-dependent manner and/or by manual operator control.
 6. A method of controlling an operation of an exhaust hood arranged above a cooking appliance having one or more cooking areas, the method comprising the following steps: detecting a temperature of at least one cooking area of the cooking appliance; switching on a fan apparatus of the exhaust hood depending on the detected temperature; detecting cooking vapors in the discharge air being drawn away by suction with the fan apparatus; and controlling a suction-removal power of the fan apparatus depending on the cooking vapors which are detected.
 7. The method according to claim 6, which comprises switching on the fan apparatus at a low power level depending on the detected temperature.
 8. The method according to claim 6, which comprises; separately detecting respective temperatures of several cooking areas of the cooking appliance; and controlling separate streams of discharge air of the fan apparatus from individual cooking areas of the cooking appliance depending on the detected temperatures.
 9. The method according to claim 6, which comprises switching off the fan apparatus of the exhaust hood depending on a detected temperature of at least one cooking area of the cooking appliance, depending on detected cooking vapors, in a time-dependent manner and/or by manual operator control. 